CIRCUIT FOR DECODING VARIABLE-LENGTH CODE, AND SYSTEM FOR DECODING VARIABLE-LENGTH CODE WHICH USES THE CIRCUIT

摘要

A circuit comprising a pair of a CAM cell (10) for storing variable-length codes and a RAM cell (20) for storing data used for mask processing. This circuit further has an NMOS (30) which is connected between the CAM cell (10) and a match line ML, and cuts off the CAM cell (10) from the match line ML by use of the output of the RAM cell (20). The CAM cell (10) checks a code applied from the outside with the code stored in it. If these codes are agreed with each other, the CAM cell (10) outputs an H level signal which represents the agreement to the match line ML. If disagreed, it outputs an L level signal which represents the disagreement to the match line ML. If the CAM cell does not engage in the checking operation, the corresponding RAM cell (20) outputs an L level signal to turn off the NMOS (30). When the NMOS is turned off, the output from the CAM cell (10) is not transmitted to the match line ML.